Recycled Concrete Aggregate Containing Rice Husk Ash as Partial Replacement for Cement for Low Cost Housing in Kenya
Chapter 1
INTRODUCTION
Currently Kenya has taken a major initiative on developing the infrastructures such as express highways, power projects and industrial structures, to meet the vision 2030 in the requirements of globalization in the construction of buildings and other structures. Concrete is the premier construction material across the world and the most widely used in all types of civil engineering works, including infrastructure, low and high-rise buildings, defense installations, environment protection and local/domestic developments (Parekh and Modhera, 2011). Aggregates is one of the constituents used in the production of conventional concrete and has become highly expensive and also scarce. The growing environmental concerns, increasing scarcity of landfills, rapidly depleting sources of quality (virgin) aggregate in some regions coupled with the increasing haulage and growing landfill costs are the driving forces promoting the recycling of concrete demolition waste in new concrete (Roz-Ud-Din and Soroushian, 2012). Therefore due to the rising costs and the environmental concerns, there is large demand for alternative materials from industrial waste.
Construction industry does not yet have a simple and cost effective method to use the recycled aggregates in second generation concrete. Works on recycled aggregate concrete have considered water absorption and other parameters in finding the mix proportions and strength but this is not sufficient since the percentage and quality of the adhered mortar is essential in calculating the final strength of concrete without adding the cost towards processing (Yadav and Pathak, 2009). Though other concrete parameters discussed by some researchers are essential in evaluating and obtaining strength of concrete, still a methodology taking into consideration the quality and the % of adhered mortar would be essential if recycled aggregates have to be taken in preparation of high strength concrete. This will be of
INTRODUCTION
Currently Kenya has taken a major initiative on developing the infrastructures such as express highways, power projects and industrial structures, to meet the vision 2030 in the requirements of globalization in the construction of buildings and other structures. Concrete is the premier construction material across the world and the most widely used in all types of civil engineering works, including infrastructure, low and high-rise buildings, defense installations, environment protection and local/domestic developments (Parekh and Modhera, 2011). Aggregates is one of the constituents used in the production of conventional concrete and has become highly expensive and also scarce. The growing environmental concerns, increasing scarcity of landfills, rapidly depleting sources of quality (virgin) aggregate in some regions coupled with the increasing haulage and growing landfill costs are the driving forces promoting the recycling of concrete demolition waste in new concrete (Roz-Ud-Din and Soroushian, 2012). Therefore due to the rising costs and the environmental concerns, there is large demand for alternative materials from industrial waste.
Construction industry does not yet have a simple and cost effective method to use the recycled aggregates in second generation concrete. Works on recycled aggregate concrete have considered water absorption and other parameters in finding the mix proportions and strength but this is not sufficient since the percentage and quality of the adhered mortar is essential in calculating the final strength of concrete without adding the cost towards processing (Yadav and Pathak, 2009). Though other concrete parameters discussed by some researchers are essential in evaluating and obtaining strength of concrete, still a methodology taking into consideration the quality and the % of adhered mortar would be essential if recycled aggregates have to be taken in preparation of high strength concrete. This will be of
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